As of 2012, over a hundred million people have been using newly shipped tablets with multi-touch screens. Additionally, over half a billion smartphones possess multi-touch screens. All these devices enable and display on their screens user drawings and handwritten notes made with one or more fingers or employing special styluses. Note-taking and markup software application such as Evernote® Penultimate and Evernote® Skitch, both developed by the Evernote® Corporation of Redwood City, Calif., and many other software titles with digital ink entry, have become mass market products with millions of users. Accordingly, user interfaces (UIs) for stylus and pen based note-taking are gaining increasing attention by researchers, developers and public.
One apparent usability challenge faced by multi-touch and other pen-enabled UIs results from the fact that a stylus or a finger applied to a multi-touch screen or other writing-enabled surface is used for drawing and handwriting and is also used for object manipulation, navigation and editing. The necessity of coupling writing or drawing with manipulating and editing of previously entered objects, performed almost simultaneously and in a random order of the two types of activities, may cause conflicts and makes the design of intuitive UIs for extensive drawing, markup and handwritten note-taking a difficult task.
Software titles that support creation and editing of vector objects, such as editable digital ink, freehand shapes, or other instantly transformable objects may provide a special object manipulation mode where drawing and instant freehand transformations are prohibited; any multi-touch gestures or stylus movements over the screen in such object manipulation mode are interpreted as selection, editing and manipulations of vector objects and other items. When users need to enable writing and freehand shape editing, they press special tool buttons permanently present in the software toolbar. While such multi-mode design is conventional for high-end authoring tools and arguably resolves the conflict between drawing and object manipulations, such a design may overload product UIs and makes note-taking tools more complex and demanding (and respectively less intuitive and productive) for a broad user base.
Another challenge faced by user interfaces for multi-touch devices with writing and drawing capabilities is caused by an inefficient grouping of handwriting and drawing objects in the authoring software. A conventional grouping metaphor may be based purely on a line continuity so that any advanced grouping is deferred to the above-mentioned object manipulation mode.
Accordingly, it is desirable to provide simple user interface metaphors for multi-touch note-taking software products with a seamless combination between drawings/writing and on-screen object manipulations and with automatic enhanced object grouping.